In recent years, vehicles driven by electric power have been used.
This leads to a need for supplying electric power to a vehicle.
For example, electric power is supplied to a parked vehicle by a power supply apparatus.
The power supply apparatus is capable of supplying electric power to a vehicle in a wireless manner.
For example, such an idea has been studied that a vehicle has a wireless type power supply secondary coil on a bottom part thereof, and a power supply primary coil is provided below the vehicle to supply electric power to the vehicle.
FIGS. 16A and 16B are conceptual diagrams of a wireless power transfer system.
The concept illustrated in FIGS. 16A and 16B has been disclosed in U.S. Pat. No. 8,035,255.
When the wireless type is employed, it is desired that power is supplied with a small energy loss from the power supply primary coil to the power supply secondary coil.